The Longgouhe and Ershiyizhan intrusions of the Late Jurassic, located in the Upper Heilongjiang Basin of the northern Great Hinggan Range, are closely related to porphyry Cu-Au mineralizations. In lithology the intru...The Longgouhe and Ershiyizhan intrusions of the Late Jurassic, located in the Upper Heilongjiang Basin of the northern Great Hinggan Range, are closely related to porphyry Cu-Au mineralizations. In lithology the intrusions are quartz diorite, quartz monzodiorite and granodiorite of high-K caIc-alkaline series, with minor aspects of shoshonite series. Their SiO2 and A1203 contents range from 61.37% to 66.59% and 15.35% to 17.06%, respectively. The MgO content ranges from 2.02 % to 3.47 %, with Mg# indices of 44-59. The （La/Yb）N and Eu/Eu＊ values range from 16.85 to 81.73 and 0.68 to 0.93, respectively, showing strong differentiation rare earth element （REE） patterns similar to those of adakites. The rocks are enriched in Ba, Sr and light REE （LREE）, obviously depleted in Nb and Ta, slightly depleted in Rb and Ti, and poor in Yb and Y, with Yb and Y contents of 0.31-1.32 ppm and 4.32-12.07 ppm, respectively. As indicated by Sr/Y ratios of 67.74-220.60, the rocks are characterized by low-Y and high-Sr contents, which characterize the adakites in the world. Holistically, geochemical tracers suggest that the interested intrusions are adakitic rocks. Given that the Paleo- Asian Ocean and Mongol-Okhotsk Ocean were closed in the Late Paleozoic and Permian-Middle Jurassic, respectively, the interested intrusions should be formed by partial melting of delaminated crust, which had been thickened during collisional orogeny between the Siberian and Mongolian- Sinokorean continents.展开更多
The Luoguhe intrusion, located in MoheCounty, Heilongjiang Province, is mainly composed of mon-zogranite, quartz diorite and granodiorite, with minor dio-rite, tonalite, quartz monzodiorite, quartz monzonite, syeno-gr...The Luoguhe intrusion, located in MoheCounty, Heilongjiang Province, is mainly composed of mon-zogranite, quartz diorite and granodiorite, with minor dio-rite, tonalite, quartz monzodiorite, quartz monzonite, syeno-granite and alkali-feldspar granite. The intrusion can bedivided into two lithological units, i.e. quartz diorite andmonzogranite units, with affinities to high-K calc-alkalineseries. The quartz diorite unit (SiO2: 54.79%―58.30%Na2O/CaO: 0.79―1.53 and Shand index: 0.77―0.82) belongsto metaluminous rocks. And the monzogranite unit (SiO2:65.29%―66.45%, Na2O/CaO: 1.73―3.43 and Shand index<1.05) can be considered as weakly peraluminous rocks. Theintrusion is characterized by high REE abundance (∑REE =180.2―344.3 μg/g), medium-strong negative Eu anomalies(δ Eu = 0.33―0.82), weak REE fractionation [(La/Yb)N =4.12―10.45], enrichments in Rb, Th, U, K, La, Ce, Nd, HfZr and Sm, but strong depletions of Ba, Nb, Ta, Sr, P and TiThese characteristics of major, REE and trace elements in-dicate that the intrusion was formed in a transitional tectonicsetting from compressional to extensional regime, which canbe classified as post-collisional granitoids. SHRIMP U-Pbzircon analyses yield ages of 517±9 and 504±8 Ma for thequartz diorite and monzogranite units, respectively. The dis-covery of Early Paleozoic post-collisional granites in thenorthern margin of the Erguna massif indicates that thenorthern branch of Paleo-Asian Ocean between Siberianplate and Erguna massif was closed in the Early Paleozoicand the Salair orogeny ended ca. 500 Ma ago.展开更多
基金supported by the Major State Basic Research Program of People's Republic of China (Grant Nos.2006CB403508 and 2007CB411303)the National Natural Science Foundation of China(Nos. 40772055 and 40425006)+1 种基金National Key Technology R&D Program(No.2007BAB25B03)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘The Longgouhe and Ershiyizhan intrusions of the Late Jurassic, located in the Upper Heilongjiang Basin of the northern Great Hinggan Range, are closely related to porphyry Cu-Au mineralizations. In lithology the intrusions are quartz diorite, quartz monzodiorite and granodiorite of high-K caIc-alkaline series, with minor aspects of shoshonite series. Their SiO2 and A1203 contents range from 61.37% to 66.59% and 15.35% to 17.06%, respectively. The MgO content ranges from 2.02 % to 3.47 %, with Mg# indices of 44-59. The （La/Yb）N and Eu/Eu＊ values range from 16.85 to 81.73 and 0.68 to 0.93, respectively, showing strong differentiation rare earth element （REE） patterns similar to those of adakites. The rocks are enriched in Ba, Sr and light REE （LREE）, obviously depleted in Nb and Ta, slightly depleted in Rb and Ti, and poor in Yb and Y, with Yb and Y contents of 0.31-1.32 ppm and 4.32-12.07 ppm, respectively. As indicated by Sr/Y ratios of 67.74-220.60, the rocks are characterized by low-Y and high-Sr contents, which characterize the adakites in the world. Holistically, geochemical tracers suggest that the interested intrusions are adakitic rocks. Given that the Paleo- Asian Ocean and Mongol-Okhotsk Ocean were closed in the Late Paleozoic and Permian-Middle Jurassic, respectively, the interested intrusions should be formed by partial melting of delaminated crust, which had been thickened during collisional orogeny between the Siberian and Mongolian- Sinokorean continents.
基金This work was supported by the National Resources Compensation from the Ministry of Land Mineral Resources of China(Grant No.2001170191).
文摘The Luoguhe intrusion, located in MoheCounty, Heilongjiang Province, is mainly composed of mon-zogranite, quartz diorite and granodiorite, with minor dio-rite, tonalite, quartz monzodiorite, quartz monzonite, syeno-granite and alkali-feldspar granite. The intrusion can bedivided into two lithological units, i.e. quartz diorite andmonzogranite units, with affinities to high-K calc-alkalineseries. The quartz diorite unit (SiO2: 54.79%―58.30%Na2O/CaO: 0.79―1.53 and Shand index: 0.77―0.82) belongsto metaluminous rocks. And the monzogranite unit (SiO2:65.29%―66.45%, Na2O/CaO: 1.73―3.43 and Shand index<1.05) can be considered as weakly peraluminous rocks. Theintrusion is characterized by high REE abundance (∑REE =180.2―344.3 μg/g), medium-strong negative Eu anomalies(δ Eu = 0.33―0.82), weak REE fractionation [(La/Yb)N =4.12―10.45], enrichments in Rb, Th, U, K, La, Ce, Nd, HfZr and Sm, but strong depletions of Ba, Nb, Ta, Sr, P and TiThese characteristics of major, REE and trace elements in-dicate that the intrusion was formed in a transitional tectonicsetting from compressional to extensional regime, which canbe classified as post-collisional granitoids. SHRIMP U-Pbzircon analyses yield ages of 517±9 and 504±8 Ma for thequartz diorite and monzogranite units, respectively. The dis-covery of Early Paleozoic post-collisional granites in thenorthern margin of the Erguna massif indicates that thenorthern branch of Paleo-Asian Ocean between Siberianplate and Erguna massif was closed in the Early Paleozoicand the Salair orogeny ended ca. 500 Ma ago.
